水稻密穗突变体A989突变基因克隆和转基因植株分析

Dense-Panicle-Related Gene Cloning from Rice Mutant A989 and Transgenic Plant Analysis

从水稻T-DNA插入突变群体中分离得到一个密穗突变体A989,表现晚开花、穗二级枝梗和小花数增加以及包颈。分子检测证明A989中T-DNA是单拷贝插入,通过inverse PCR的方法分离得到A989中T-DNA的旁邻序列,表明T-DNA插入在RCN2基因polyA加A位点后330bp处;RT-PCR检测发现在A989中,RCN2基因的表达被显著上调。利用2×35S启动子在野生型水稻Zhonghua 11中超表达RCN2基因,转基因植株表现为不抽穗,通过细胞学观察发现转基因植株能完成营养生长向生殖生长的转变,但是生殖生长期的分生组织在分化出二级枝梗原基后停止分化和生长。此外,通过比较部分开花相关基因在野生型Zhonghua 11、突变体A989中的表达,推测了RCN2基因可能的作用途径。

Rice（Oryza sativa L.） is a model monocotyledonous plant for genetic study due to its small genome size.Along with the completion of genome sequencing,gene cloning and function study becomes the most important task.The concomitant methodology of reverse genetics has played fundamental roles in identifying and studying rice genes in recent years.Rice heading time and inflorescence architecture are two inter-relating and agriculturally important characters.In Arabidopsis,TFL1 gene takes part in the configuration process and transition of growth stage,including flowering.In rice,there are four TFL1 gene homologies,RCN1-4,over-expression of any one of which could result in delayed flowering and abnormal inflorescence architecture.In this study,a mutant A989 with the trait of dense panicle and late flowering was isolated from our T-DNA insertion population.Genetic and molecular analysis proved that in mutant A989,insertion of T-DNA nearby the RCN2 gene caused its over-expression,and resulted in the phenotype of dense panicle and late flowering.We further made RCN2 gene over-expressed driven by double 35S promoter,and analyzed trait of the transformants.Possible pathway of RCN2 gene function was discussed.